<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    .box {
      position: relative;
      background: red;
      color: white;
      height: 200px;
    }
    .box > div:last-child {
      width: 60px;
      height: 30px;
      background-color: rgba(255, 255, 255, 0.4);
      backdrop-filter: blur(2px);
      position: absolute;
      top: 0;
    }
  </style>
</head>
<body>
<div class="box">
  <div>我是背后的文字</div>
  <div></div>
</div>
</body>
</html>